Reference electrode

ABSTRACT

A reference structure and a separator assembly is provided. The separator assembly provides a base layer, a first contact, an optional second contact and a reference component which may be implemented in various applications. The base layer includes a first side and a second side. The first contact is affixed on the first side of the base layer between the base layer and an anode. The second contact is affixed on the second side of the base layer. A reference component is affixed to the second side of the base layer and the optional second contact, if implemented. The reference structure includes a semi-permeable reference component affixed or coupled to a base element.

TECHNICAL FIELD

The present disclosure relates generally to the field of lithium-ionbatteries and battery modules. More specifically, the present disclosurerelates to a reference electrode which may be integrated with a basemember such as but not limited to a separator used in a vehicle batterycell, as well as other energy storage/expending applications.

BACKGROUND

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present disclosure,which are described below. This discussion is believed to be helpful inproviding the reader with background information to facilitate a betterunderstanding of the various aspects of the present disclosure.Accordingly, it should be understood that these statements are to beread in this light, and not as admissions of prior art.

A vehicle that uses one or more battery systems for providing all or aportion of the motive power for the vehicle can be referred to as anxEV, where the term “xEV” is defined herein to include all of thefollowing vehicles, or any variations or combinations thereof, that useelectric power for all or a portion of their vehicular motive force. Forexample, xEVs include electric vehicles (EVs) that utilize electricpower for all motive force. As will be appreciated by those skilled inthe art, hybrid electric vehicles (HEVs), also considered xEVs, combinean internal combustion engine propulsion system and a battery-poweredelectric propulsion system, such as 48 Volt (V) or 130V systems. Theterm HEV may include any variation of a hybrid electric vehicle. Forexample, full hybrid systems (FHEVs) may provide motive and otherelectrical power to the vehicle using one or more electric motors, usingonly an internal combustion engine, or using both. In contrast, mildhybrid systems (MHEVs) disable the internal combustion engine when thevehicle is idling and utilize a battery system to continue powering theair conditioning unit, radio, or other electronics, as well as torestart the engine when propulsion is desired. The mild hybrid systemmay also apply some level of power assist, during acceleration forexample, to supplement the internal combustion engine. Mild hybrids aretypically 96V to 130V and recover braking energy through a belt or crankintegrated starter generator. For the purposes of the presentdiscussion, it should be noted that mHEVs typically do not technicallyuse electric power provided directly to the crankshaft or transmissionfor any portion of the motive force of the vehicle, but an mHEV maystill be considered as an xEV since it does use electric power tosupplement a vehicle's power needs when the vehicle is idling withinternal combustion engine disabled and recovers braking energy throughan integrated starter generator. In addition, a plug-in electric vehicle(PEV) is any vehicle that can be charged from an external source ofelectricity, such as wall sockets, and the energy stored in therechargeable battery packs drives or contributes to drive the wheels.PEVs are a subcategory of EVs that include all-electric or batteryelectric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), andelectric vehicle conversions of hybrid electric vehicles andconventional internal combustion engine vehicles.

xEVs as described above may provide a number of advantages as comparedto more traditional gas-powered vehicles using only internal combustionengines and traditional electrical systems, which are typically 12Vsystems powered by a lead acid battery. For example, xEVs may producefewer undesirable emission products and may exhibit greater fuelefficiency as compared to traditional internal combustion vehicles and,in some cases, such xEVs may eliminate the use of gasoline entirely, asis the case of certain types of EVs or PEVs.

As xEV technology continues to evolve, there is a need to provideimproved power sources (e.g., battery systems or modules) for suchvehicles. For example, it is desirable to increase the distance thatsuch vehicles may travel without the need to recharge the batteries.Additionally, it may also be desirable to optimize the performance ofsuch batteries and to reduce the cost associated with the batterysystems by monitoring the state of charge for the battery cells. Forinstance, it is now recognized that it may be desirable to provide afeature which is part of the battery module and is capable of providingthe status of the battery cell which includes but is not limited to thestate of charge (SOC).

SUMMARY

A summary of certain embodiments disclosed herein is set forth below. Itshould be understood that these aspects are presented merely to providethe reader with a brief summary of these certain embodiments and thatthese aspects are not intended to limit the scope of this disclosure.Indeed, this disclosure may encompass a variety of aspects that may notbe set forth below.

A battery cell separator assembly provides a base layer, a firstcontact, a second contact and a reference component. The base layerincludes a first side and a second side. The first contact is affixed onthe first side of the base layer between the base layer and an anode.The second contact is affixed on the second side of the base layer. Areference component is disposed on the second contact. The battery cellseparator assembly may be implemented in a variety of locations, suchas, but not limited to, a vehicle battery for on-board vehicle use aswell as in a battery cell test fixture.

A battery cell system is also provided which includes: an anode, acathode, a separator formed from a base layer, first and second contactsand a reference component. The anode and cathode are disposed in alithium ion non-aqueous solution within a housing. The base layer of theseparator includes a first side and a second side. The base layer isoperatively configured to separate the anode and the cathode within thehousing. The first contact of the separator is affixed to the first sideof the base layer between the base layer and an anode. The secondcontact is affixed to the second side of the base layer with thereference component disposed on the second contact.

Additionally, a battery cell testing fixture may also be provided whichincludes: a stand, a housing, a meter and a separator formed from a baselayer, first and second contacts and a reference component. The housingis operatively configured to hold an anode and a cathode in a lithiumion solution and is disposed on or affixed to the stand. The separatorincludes a base layer having a first side and a second side disposed inthe lithium ion solution. The base layer is operatively configured toseparate the anode and the cathode in the lithium ion solution disposedwithin a housing. The first contact may be affixed to the first side ofthe base layer so that the first contact is positioned directly betweenthe base layer and the anode. The second contact may be affixed to thesecond side of the base layer and used as a base for the referencecomponent. A meter may be in communication with the reference componentvia the second contact such that the meter reads the voltage differencebetween the reference component and (1) anode current collector locatedon the backside of the anode; and (2) the first contact located on thefront side of the anode.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present disclosure willbe apparent from the following detailed description of preferredembodiments, and best mode, appended claims, and accompanying drawingsin which:

FIG. 1 is a perspective view of an xEV having a battery systemconfigured in accordance with the embodiments of the present disclosureto provide power for various components of the xEV.

FIG. 2 is a cutaway schematic view of an embodiment of the xEV havingthe separator assembly and battery system of FIG. 1 and having a lithiumion battery in accordance with an aspect of the present disclosure.

FIG. 3A is a schematic view of the second side of a base layer(separator) with the porous gold contact layer and porous referencecomponent affixed to the second side of the base layer.

FIG. 3B is a schematic view of the first side of the base layer(separator) with the porous copper contact layer affixed to the firstside of the base layer.

FIG. 4A is a cross-sectional schematic view of a battery cell system inaccordance with multiple embodiments of present disclosure.

FIG. 4B is a schematic cross-sectional view of an embodiment of thebattery cell test fixture of the present disclosure implemented with atest anode.

FIG. 4C is a schematic cross-sectional view of an embodiment of thebattery cell test fixture of the present disclosure implemented with atest cathode.

FIG. 5 is an enlarged, side schematic view of the separator assembly ofthe present disclosure relative to an anode for a vehicle battery.

FIG. 6A is a magnified cross sectional view of an embodiment of thepresent disclosure where the reference component is affixed directly tothe base layer or base element.

FIG. 6B is a magnified plan view of an embodiment of the presentdisclosure where the reference component is affixed directly to the baselayer or base element.

Like reference numerals refer to like parts throughout the descriptionof several views of the drawings.

DETAILED DESCRIPTION

One or more specific, example embodiments will be described below. In aneffort to provide a concise description of these embodiments, not allfeatures of an actual implementation are described in the specification.It should be appreciated that in the development of any such actualimplementation, as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

The terms “first,” “second,” and the like, herein do not denote anyorder, quantity, or importance, but rather are used to distinguish oneelement from another, and the terms “a” and “an” herein do not denote alimitation of quantity, but rather denote the presence of at least oneof the referenced items.

The battery systems described herein may be used to provide power to anumber of different types of xEVs as well as other energy storageapplications (e.g., electrical grid power storage systems). Such batterysystems may include one or more battery modules, each battery modulehaving a number of battery cells (e.g., lithium ion electrochemicalcells) arranged to provide particular voltages and/or currents useful topower, for example, one or more components of an xEV. Generally, thebattery cells include electrochemical materials (e.g., electrolytes,electrode active materials), which are responsible for much of theelectrical activity of the battery cell. The electrochemical materialsare housed within, and supported by, certain mechanical features of thecell, such has a housing 6 of the battery cell, a current collector ofthe battery cell, and so forth.

A more detailed view of the battery system 12 is described in FIG. 2. Asdepicted, the vehicle propulsion system 8 may include an energy storagecomponent 14 coupled to an ignition system 16, an alternator 18, avehicle console 20, and optionally to an electric motor 22. Generally,the energy storage component 14 may capture/store electrical energygenerated in the vehicle 10 and output electrical energy to powerelectrical devices in the vehicle 10. The energy storage component 14may further include the lithium ion battery cell system 28 of thepresent disclosure and a lead acid battery 30.

In other words, the vehicle propulsion system 8 may supply power tocomponents of the vehicle's electrical system, which may includeradiator cooling fans, climate control systems, electric power steeringsystems, active suspension systems, auto park systems, electric oilpumps, electric super/turbochargers, electric water pumps, heatedwindscreen/defrosters, window lift motors, vanity lights, tire pressuremonitoring systems, sunroof motor controls, power seats, alarm systems,infotainment systems, navigation features, lane departure warningsystems, electric parking brakes, external lights, or any combinationthereof. Illustratively, in the depicted embodiment, the energy storagecomponent 14 supplies power to the vehicle console 20 and the ignitionsystem 16, which may be used to start (e.g., crank) the internalcombustion engine 24.

Additionally, the energy storage component 14 may capture electricalenergy generated by the alternator 18 and/or the electric motor 22. Insome embodiments, the alternator 18 may generate electrical energy whilethe internal combustion engine 24 is running. More specifically, thealternator 18 may convert the mechanical energy produced by the rotationof the internal combustion engine 24 into electrical energy.Additionally or alternatively, when the vehicle 10 includes an electricmotor 22, the electric motor 22 may generate electrical energy byconverting mechanical energy produced by the movement of the vehicle 10(e.g., rotation of the wheels) into electrical energy. Thus, in someembodiments, the energy storage component 14 may capture electricalenergy generated by the alternator 18 and/or the electric motor 22during regenerative braking. As such, the alternator and/or the electricmotor 22 are generally referred to herein as a regenerative brakingsystem.

To facilitate capturing and supplying electric energy, the energystorage component 14 may be electrically coupled to the vehicle'selectric system via a bus 26. For example, the bus 26 may enable theenergy storage component 14 to receive electrical energy generated bythe alternator 18 and/or the electric motor 22. Additionally, the bus 26may enable the energy storage component 14 to output electrical energyto the ignition system 16 and/or the vehicle console 20. Accordingly,when a 12 volt battery system 12 is used, the bus 26 may carryelectrical power typically between 8-18 volts.

Additionally, as depicted, the energy storage component 14 may includemultiple battery modules. For example, in the depicted embodiment, theenergy storage component 14 includes a lithium ion battery 28 and alead-acid battery 30, which each includes one or more battery cells. Inother embodiments, the energy storage component 14 may include anynumber of battery modules. Additionally, although the lithium ionbattery module 28 and lead-acid battery module 30 are depicted adjacentto one another, they may be positioned in different areas around thevehicle. For example, the lead-acid battery module may be positioned inor about the interior of the vehicle 10 while the lithium ion batterymodule 28 may be positioned under the hood of the vehicle 10.

To facilitate controlling the capturing and storing of electricalenergy, the propulsion system 8 may additionally include a controlmodule 32. More specifically, the control module 32 may controloperations of components in the battery system 12, such as relays (e.g.,switches) within energy storage component 14, the alternator 18, and/orthe electric motor 22. For example, the control module 32 may regulateamount of electrical energy captured/supplied by each battery module 28or 30, perform load balancing between the battery modules 28 and 30,determine a state of charge of each battery module 28 or 30, determinetemperature of each battery module 28 or 30, control voltage output bythe alternator 18 and/or the electric motor 22, and the like.

In accordance with at least selected embodiments or objects, one aspectof the present disclosure provides a separator for a lithium-ionbattery, such as, for example, a lithium ion battery (though the use ofthe separator is contemplated with other batteries as well), whichseparator 36 comprises a porous, permeable or semi permeable compositehaving a microporous substrate and a coating layer formed on at leastone surface of the porous substrate, wherein the coating layer is formedfrom particles and/or a mixture of particles (inorganic and/or organicparticles) and an aqueous or water-based polymeric binder.

The separator assembly 36 described herein may be advantageous becauseof its added ability to provide the status of a cell of a lithium ionbattery. This improved, optimized, new, or modified separator for alithium ion battery includes a base layer 34. The base layer 34 may becoated with a mixture of one or more types of particles (e.g., inorganicparticles, such as, for example, ceramic particles, and/or organicparticles, such as, for example, high temperature polymer particles) andone or more aqueous or water-based polymeric binders, where an aqueousor water-based polymeric binders may include one or more typicallywater-insoluble polymers (such as PVDF and/or various copolymersthereof) and may, in certain embodiments, further include one or moretypically water-soluble polymers (such as, by way of example, polyvinylalcohol or polyacrylic acid). The coating layer may prevent oxidationreactions from occurring at the interfaces of the coated separator andthe electrodes in the battery and/or may improve the safety and/or theoverall performance of a lithium ion battery.

As indicated, the ceramic coating helps to maintain the integrity of thebase layer 34 of the separator. The particles can be of a variety ofshapes, such as, but not limited to, rectangular, spherical, elliptical,cylindrical, oval, dog-bone shaped, or amorphous. The “particles” canalso be fibrous-shaped or fibers. The particles in some embodiments arequite small and thus may have a large surface area per gram, which mayenhance the absorption performance of the coating material and theinteraction of the particles with the polymer matrix. Furthermore, insome embodiments, the particles, as purchased from the particlemanufacturer, may, for example, be pre-coated with some material toenhance the compatibility of the particle with a polymeric matrix, toimprove, possibly making more uniform, the dissolution of the particlesin some portion of the polymer matrix, the dispersibility of theparticles in the polymer matrix, to avoid particle agglomeration, and/orto stabilize the particles in the coating slurry.

It is understood that the base layer, the reference component, theseparator assembly 36, the first contact 38 and the optional secondcontact 40 described herein may be referenced as being permeable,semi-permeable or porous throughout the present disclosure. Regardlessof the term which is used—“permeable,” “semi-permeable” or “porous”should be all be construed to mean that ions may pass through suchmaterial in a variety of degrees depending on the type of material usedfor (and the process used to manufacture/assemble such assputtering/screen printing/painting/etc) the base layer, referencecomponent, separator assembly, and/or first/second contacts.

With reference to FIGS. 3A-3B, 4A and 5, a battery cell separatorassembly 36 in accordance with the present disclosure may include a baselayer 34, a first contact 38, an optional second contact 40 and areference component 42. While the base layer 34 in FIGS. 3A-3B is shownas circular, the base layer 34 may take any shape such as a square orrectangle, etc. depending on the configuration of the battery cell.Optional second contact 40 is shown in dashed lines to indicate thatsecond contact 40 may not be used and the reference component 42 maythen therefore be affixed directly to the base layer 34—as shown in FIG.6. The base layer 34 may a first side 44 and a second side 46 as shown.The first contact 38 may, but not necessarily, be formed from copper ifused with an anode electrode. Also, the first contact 38 may, but notnecessarily be formed from gold if used with cathode electrode. Theoptional second contact 40 may but not necessarily be formed from goldor other similar low resistance material. Referring to FIG. 4A inparticular, an optional middle separator 35 is shown which prevents thereference material 42 from touching any structure other than the baselayer and/or the optional second contact 40. It is understood that inlieu of using an optional middle separator as shown in FIG. 4A, thereference material may be powdered or coated with a ceramic material orthe like to protect the reference material against short circuiting inthe event it contacts other structures in the battery.

As shown in FIGS. 3A-3B, 4A and 5, the first contact 38 may be affixedon the first side 44 of the base layer 34 such that the first contact 38is “sandwiched” between the base layer 34 and an electrode 48 which maybe an anode or a cathode. In this arrangement, the first contact 38 isproximate to or adjacent to the electrode 48 as shown in FIG. 5. Theoptional second contact 40, when implemented, may be disposed on thesecond side 46 of the base layer 34; and a reference component 42 may bedisposed on the second contact 40.

The reference component 42 is operatively configured to be porous and/ormay allow lithium ions 54 to pass through the reference component 42.The porous construction is achieved by spraying on or screen printing(or similar process) the material onto the base layer 34 which may havea ceramic coating. The resulting arrangement for reference component 42is visible in FIGS. 6A and 6B. The reference component may be formedfrom material such as iron phosphate, lithium titanate, or another likemetal oxide. It is understood that the reference component 42 is formedfrom a material which has a constant voltage (or does not vary much) nomatter what the state of charge is—with the exception of very low orvery high state of charge. By having a constant voltage, the referencecomponent 42 allows a user/system to compare the fixed voltage to otherpoints in a system. Moreover, the reaction kinetics of the referencecomponent 42 material should be facile in order that the small amount ofcurrent flow permitted by the meter 56 in order to obtain a measurementof voltage differences 58, 60 should not cause polarization of thereference voltage itself.

It is understood that the metal oxide used for the reference component42 may be mixed with a hydrocarbon binder and a solvent such that aslurry is formed. The reference component 42 then may be sprayed, screenprinted or drawn out onto the second contact 40 in order to make thereference component 42 porous to allow lithium ions 54 to pass throughthe reference component 42 itself. Moreover, the base layer 34 may alsobe formed from filler material enabling or causing anisotropicelectrical and/or thermal conduction. For example, the base layer 34 mayinclude nanomaterials such as metallic, semi-metallic, or carbon-basednanoparticles, nanotubes, nanofibers, sheets or layers of graphene, orthe like. Further, certain fillers may be used to provide enhancedstructural characteristics. In addition to or in lieu of conductivefillers, structural fillers may be used, such as fibers, beads,granules, or the like, of a ceramic material, such a silicate orborosilicate glass, or any other suitable material. The base layer 34may also include porous material such as polyolefin (e.g., polyethylene,polypropylene), a polyarene (e.g., polystyrene, polyphenylene sulfide),or the like which further allow for lithium ions 54 to pass through thebase layer 34.

Referring again to FIGS. 4A and 5, the battery cell separator assembly36 may also include a meter 56 operatively configured to read a firstvoltage 58 difference between the first contact 38 and the secondcontact 40 (and reference component 42) via a first circuit 62 orelectrical communication therebetween. It is understood that the samemeter 56 or another meter may be implemented which reads a secondvoltage 60 between the second contact 40 (and reference component 42)and an anode current collector 80 via a second circuit 64 or electricalcommunication therebetween.

With respect to all embodiments of the present disclosure, the secondvoltage 60 reading (from the back of the anode/cathode) may be comparedwith the first voltage 58 reading (from the front side 66 of theanode/cathode) in order to determine the health of the electrode 48(anode/cathode), stability of the electrode 48 as well as the SOC of theelectrode 48 among other factors. All of this data may be used invarious settings. In a product development or laboratory setting, thedata could be used to develop a mathematical model for a particularbattery such that the mathematical model could be implemented on suchbatteries when used on production level, operating vehicles. Themathematical model would be implemented (in lieu of a wired voltmeterand associated circuits in the batter) to provide real-time batteryfeedback to a vehicle user or to a remote location which may bemonitoring or managing the battery. Alternative to using the first andsecond voltages and other battery data to develop a mathematical model,the data may be simply routed from the circuits and voltmeter 56 to acontrol module which then communicates the data and/or batteryconditions to vehicle user (where the separator assembly 36 is used on aworking vehicle) or to a remote location or user. A non-limiting examplewhere remote battery monitoring may be useful is in an electric fleetvehicle where battery charges and battery health may be managedremotely. Accordingly, the resulting data and/or model can be usedaccurately identify the SOC and to protect the battery (ex: identifylithium plating on anode; or data may notify user when battery limitsare achieved or nearing the limits in order to help protect the lithiumion battery.

It is understood that the reference component 42 may be used in avariety of environments where it is desirable to have an unobtrusivereference electrode which could be affixed to any base element.Accordingly, the reference electrode of the present disclosure includesa porous reference component 42 wherein base layer 34 can be any baseelement 34 (not necessarily a separator or base layer 34 for a separatorin a battery environment). However, similar to the battery environment,reference component 42 may be coupled to a base element 34 directly orvia an optional contact 40 where reference component 42 may be porous orsemi-permeable in that it allows a variety of ions to pass through thereference component. Accordingly, a reference structure 43 may be formedfrom the reference component 42 as described together with a baseelement 34 wherein the reference component 42 may be in electricalcommunication with at least one of an electrode current collector 80 ora first contact 38. As indicated, the reference component 42 is formedby material such as, but not limited to iron phosphate, which may becoupled to the base layer and/or optional contact via a screen printingmethod, spray painting method or the like to achieve the porous and/orsemi-permeable structure for reference component 42. To the extent acontact 40 is used, the optional contact 40 may but not necessarily besputtered onto the base element 34 such that ionic material may alsopass through the optional second contact.

Accordingly, with reference to FIG. 4A, a lithium ion battery cellsystem 28 may also be provided according to various embodiments of thepresent disclosure. The aforementioned battery cell system may beinstalled on a vehicle which provides a user with information regardingthe state of charge and battery health. The battery cell system 28 mayinclude an anode 50 and a cathode 52 disposed in a lithium ionnon-aqueous solution 74 within a hermetically sealed housing 6 inaddition to a separator 36 which is comprised of a base layer 34, afirst contact 38, an optional second contact 40 and a referencecomponent 42 which are all integrated into the separator. The base layer34 may have a ceramic coating and includes a first side 44 and a secondside 46. The base layer 34 is operatively configured to separate theanode and the cathode in the aqueous lithium ion solution 74. The firstcontact 38 is affixed to the first side 44 of the base layer 34 betweenthe base layer 34 and an anode. The optional second contact 40 isaffixed to the second side 46 of the base layer 34 and the referencecomponent 42 is disposed on the second contact 40. Both the first andsecond contacts have a porous composition which allow lithium ions 54 topass through the contacts. This porous composition is achieved byimplementing a process such as sputtering where the contact material isapplied to the base layer 34 atom by atom. The reference component 42for each electrode (shown as an anode 50 and cathode 52) also has aporous composition which allows lithium ions 54 to pass through thereference component 42. It is understood that the reference component 42may be a metal oxide which is mixed with a hydrocarbon binder and asolvent such that a slurry is formed. The reference component 42 may beapplied to the base layer 34 (or to the second contact 40 whenimplemented) via a method such as screen printing, spraying or the like.Accordingly, the reference component 42 as well as the base layer 34 andcontacts are sufficiently porous to allow lithium ions 54 to passthrough the reference component 42 and the base layer 34. The referencecomponent 42/first and second contacts in the battery cell system aresimilar to those in the separator assembly 36 in that the referencecomponent 42 may be made from material such as iron phosphate while thefirst contact 38 may be formed from material such as copper and theoptional second contact 40 may be formed from low resistance materialsuch as gold.

Moreover, the base layer 34 may also be formed from filler materialenabling or causing anisotropic electrical and/or thermal conduction.For example, the base layer 34 may include nanomaterials such asmetallic, semi-metallic, or carbon-based nanoparticles, nanotubes,nanofibers, sheets or layers of graphene, or the like. Further, certainfillers may be used to provide enhanced structural characteristics. Inaddition to or in lieu of conductive fillers, structural fillers may beused, such as fibers, beads, granules, or the like, of a ceramicmaterial, such a silicate or borosilicate glass, or any other suitablematerial. The base layer 34 may also include porous material, such asbut not limited to, polyolefin (e.g., polyethylene, polypropylene), apolyarene (e.g., polystyrene, polyphenylene sulfide), or the like whichfurther allow for lithium ions 54 to pass through the base layer 34. Thebattery system may also include a meter 56 operatively configured toread a first voltage 58 between the first contact 38 and the secondcontact 40 via a first electrical communication therebetween.

It is understood that the battery cell system 28 having a meter 56 maybe disposed on an operating electric vehicle in order to enable avehicle user to determine the health of the battery in real time via themeter 56 itself or via a vehicle control module which communicates withthe battery. It is also understood that the battery system of thepresent disclosure may engage in remote communications with a base unitso that a base unit may remotely monitor the health of the batterysystem of the present disclosure.

Accordingly, in furtherance of the objective to monitor the state ofcharge of a vehicle battery cell among other objectives, the firstcontact 38 in the battery system 28 of the present disclosure may beaffixed to the first side 44 of the base layer 34 as shown in FIG. 5.This proximate location of the first contact 38 being adjacent to thefront side 66 of the anode provides the benefit of obtaining the voltageat the front of the electrode 48 (instead of the back of the electrode48). The voltage at the front side 66 of the electrode 48 is morepertinent for some aspects of cell control or health and SOC (state ofcharge) estimations. Moreover, given that the first contact 38, optionalsecond contact 40, base layer 34, and the reference material are allformed from porous material via processes such as sputtering, spraypainting or like processes as explained herein. Therefore, theaforementioned components are all operatively configured to allowlithium ions 54 to pass through the separator assembly 36, and theseparator's integrated reference electrode 48 do not impede theoperation of the battery cell.

Accordingly, given that the first voltage 58 at the front side 66 of theelectrode 48 may be obtained while allowing lithium ion pass-through,the present disclosure provides a more accurate data feedback for theelectrode 48. Moreover, the meter 56 as provided by the presentdisclosure, is operatively configured to read a first voltage 58 betweenthe first contact 38 (proximate to the front side 66 of the electrode48) and the optional second contact 40 (associated with the referencecomponent 42) via a circuit therebetween. The meter 56 may also beoperatively configured to read a second voltage 60 between an electrodecollector 80 (adjacent to the back side 68 of the electrode 48) and theoptional second contact 40 (associated with the reference component 42).The first and second voltages from the front and back sides 66, 68 ofthe electrode 48 provide a user with accurate voltage data for theelectrode 48.

With reference to FIGS. 4B and 4C, the battery cell separator assembly36 of the present disclosure may also be implemented as part of atesting fixture 70 as provided by the present disclosure. Accordingly, abattery cell testing fixture 70 may be provided where the battery celltesting fixture 70 includes a stand 72, a base layer 34 disposed in alithium ion solution 74, a first contact 38, an optional second contact40, a reference component 42, and a meter 56. The stand 72 of thebattery cell testing fixture 70 is operatively configured to hold ananode 50 and a cathode 52 in a lithium ion solution 74. The anode 50,the cathode 52 and the lithium ion solution 74 may be disposed in ahermetically sealed housing 6 which is then disposed or affixed to thestand 72. It is also understood that a base layer 34 which functions asa separator may also be disposed in the lithium ion solution 74 in orderto separate the anode 50 and the cathode 52.

The base layer 34 may also be formed from filler material which enablesanisotropic electrical and/or thermal conduction and may be coated witha ceramic material to maintain/protect the integrity of the fillermaterial. For example, the base layer 34 may include nanomaterials suchas metallic, semi-metallic, or carbon-based nanoparticles, nanotubes,nanofibers, sheets or layers of graphene, or the like. Further, certainfillers may be used to provide enhanced structural characteristics. Inaddition to or in lieu of conductive fillers, structural fillers may beused, such as fibers, beads, granules, or the like, of a ceramicmaterial, such a silicate or borosilicate glass, or any other suitablematerial. The base layer 34 may also include polymeric material such aspolyolefin (e.g., polyethylene, polypropylene), a polyarene (e.g.,polystyrene, polyphenylene sulfide), or the like which further allow forlithium ions 54 to pass through the base layer 34. As previouslyindicated, the base layer 34 of the separator assembly 36 may alsoinclude a ceramic coating in order to maintain the integrity of the baselayer 34 of the separator in order to maintain the separation of theanode and the cathode. The base layer 34, having a first side 44 and asecond side 46, may be disposed in the lithium ion solution 74 of a testbattery cell.

The base layer 34 together with the first contact 38, the optionalsecond contact 40, and the reference component 42 form a separatorassembly 36. The first contact 38 may be affixed to the first side 44 ofthe base layer 34 between the base layer 34 and the anode in order toprovide data or the voltage at the front side 66 of the electrode 48(shown as anode 50 in FIG. 4C or cathode 52 in FIG. 4B). The batterycell testing fixture 70 provides for an electrical communication betweenthe first contact 38 and the optional second contact 40 where the meter56 may obtain a first voltage 58 between the first and second contacts.It is understood that the first contact 38 may be formed from copper orother similar conductive material which is sputtered onto the first side44 of the base layer 34 such that the first contact 38 is also porousand allows for lithium ions 54 to pass through the separator toward theanode. It is also understood that the optional second contact 40 may,but not necessarily, formed from gold or other like material. Similar tothe first contact 38, the optional second contact 40 may also besputtered onto the second side 46 of the base layer 34 so that theoptional second contact 40 is also porous and allows for lithium ions 54to pass through the separator.

As shown in FIG. 5, the optional second contact 40 may serve as anelectric conduit to the meter 56 for the otherwise high resistancereference component 42 of the separator. Accordingly, the optionalsecond contact 40 may serve as means to obtain the voltage reading (viathe meter 56) between the reference component 42 and other portions ofthe battery cell such as the anode collector 80 which may be disposed onthe back side 68 of the anode as shown and the first contact 38 whichmay be disposed proximate to the front side 66 of the anode as shown.

Similar to the reference component 42 of the separator assembly 36previously described, the reference component 42 of the battery celltesting fixture 70 may also be sprayed, screen printed (or like process)onto the second contact 40 (where used) on the second side 46 of thebase layer 34 in order to provide a porous reference component 42 whichallows lithium ions 54 to pass through the reference component 42,optional second contact 40, and base layer 34. If the optional secondcontact 40 is not used, the reference component 42 issprayed/printed/etc directly onto the coated base layer 34 of theseparator assembly 36. Similar to the previous components in theseparator assembly 36 and the battery cell system, the optional secondcontact 40 may be formed from copper or other similar material which isalso porous and allows lithium ions 54 to pass through. In order toobtain a porous structure in the second contact 40, the second contact40 may, but not necessarily, be sputtered onto the second side 46 of thebase layer 34.

The battery cell testing fixture 70 may further include a meter 56 whichis operatively configured to read a first voltage 58 between the firstcontact 38 and the reference component 42 (optionally through a secondcontact 40) via a first circuit 62 therebetween. The first voltage 58 isparticularly useful in that this voltage relates to the front side 66 ofthe electrode 48 and may be compared with the second voltage 60 from theback side 68 of the electrode 48 to determine many operating conditionsfor the tested battery cell. It is understood that the first voltage 58from the front side 66 of the electrode 48 was generally not availabledue to previous concerns about monitoring equipment impeding thepass-through of lithium ions 54. The same meter 56 for reading the firstvoltage 58 may, but not necessarily be used to also read a secondvoltage 60 between the reference component 42 (directly or via anoptional second contact 40) and a current collector 80 (at the back side68 of the electrode 48) via a second circuit 64 therebetween.Accordingly, the porous nature of the first and second contacts affixedto the base layer 34 as well as the porous nature of the referencecomponent 42 enable the battery cell test fixture to obtain a voltagereading at the front of the electrode 48 thereby providing morecomprehensive data for the electrode 48.

It is understood that the base layer 34 of the separator assembly 36used in all embodiments of the present disclosure must have anappropriate thickness wherein the base layer 34 may consist of a singlelayer of material or the base layer 34 may consist of multiple layers ofmaterial. With respect to thickness, if the base layer 34 of theseparator assembly 36 is too thin, insufficient electrical insulationmay result. On the other hand, if the base layer 34 of the separator istoo thick, insufficient thermal transfer may occur. Even in situationswhere thermal gradients are not a substantial consideration from thestandpoint of the separator 52, if the base layer 34 is too thick, theremay be also be insufficient room within the housing 6 to fit all thebattery cells with a rather thick battery cell separator 52. By way ofnon-limiting example, the base layer 34 may, but not necessarily, havean acceptable thickness between approximately 0.025 mm and approximately0.05 mm.

In yet another embodiment for the battery cell testing fixture 70 of thepresent disclosure, the testing fixture may include a user interface 86and a separator assembly 36 in communication with the user interface.The separator assembly 36 may be operatively configured to be used witha plurality of test batteries 90 in succession as each test battery isevaluated over a period of time. The separator assembly 36 includes anintegrated reference electrode formed from at least a permeablereference component 42 affixed to the base layer 34 via a screenprinting process or the like. It is understood that the permeablereference component 42 may be semi-permeable or completely permeabledepending on the degree of porosity of the reference component or thetype of material used in the reference component or the process used toaffix the reference component to the base layer 34—painting, printing orthe like. The separator assembly 36 is operatively configured tocommunicate with a current collector of one of the plurality of testbatteries 90, a meter 56 and the user interface 86.

The battery cell testing fixture 70 may, but not necessarily, include astand 72 which is coupled to at least one of the user interface 86, atest battery 90 or separator assembly 36. It is understood that theseparator assembly 36 includes a base layer having a first side and asecond side 44, 46 with the semi-permeable reference component 42coupled to the second side 46 of the base layer 34. The permeablereference component 42 may be operatively configured to allow ions 54 topass through the reference electrode (which may include the referencecomponent 42, optionally first contact 38 and second contact 40). It isunderstood that the separator assembly 36 is operatively configured toseparate the anode 50 and the cathode 52 in each of the plurality oftest batteries 90 used with the testing fixture. Similar to earlierembodiments, the permeable first contact 38 may affixed to a first side44 of the base layer via a sputtering process or the like such that thefirst contact is also permeable to ions. The first contact 38 may becommunication with the reference component 42 via a first circuit.

As shown in FIGS. 4B and 4C, the first contact is operatively configuredto be adjacent to an electrode (either the anode 50 or the cathode 52 orboth) in one of the plurality of test batteries. It is also understoodthat an optional second contact 40 may be affixed to the referencecomponent 42 and the second side 46 of the base layer. The optionalsecond contact may be in communication with a current collector of atest battery via a second circuit. Like the first contact 38, theoptional second contact 40 may also have a permeable structure and isaffixed to the base layer 34 via a sputtering process or the like inorder to achieve the permeable structure. It is understood that the userinterface 86 includes a module 88 in communication with the first andsecond circuits 62, 64 such that the module 88 may determine the statusof the test cell via a model or the like. The module then outputs thestatus of the test cell (such as the state of charge or the state of thetest cell relative to the cell limits) to a user via the user interface86.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover all modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or exemplary embodiments are only examples, and arenot intended to limit the scope, applicability, or configuration of thedisclosure in any way. Rather, the foregoing detailed descriptions willprovide those skilled in the art with a convenient road map forimplementing the exemplary embodiment or exemplary embodiments. Itshould be understood that various changes can be made in the functionand arrangement of elements without departing from the scope of thedisclosure as set forth in the appended claims and the legal equivalentsthereof.

What is claimed is:
 1. A reference structure for monitoring a status ofa cell of a battery comprising: a base element disposed adjacent anelectrode in the cell of the battery; a first contact affixed directlyto the base element; and a semi-permeable reference component affixedphysically to the base element and physically separate from a currentcollector in the cell, wherein the semi-permeable reference component isin electrical communication with at least one of the current collectorvia a second circuit and the first contact via a first circuit.
 2. Thereference structure as defined in claim 1 wherein each of thesemi-permeable reference component, the base element, and the firstcontact is operatively configured to allow ions to pass through.
 3. Thereference structure as defined in claim 1 further comprising a secondcontact disposed between and affixed directly to the semi-permeablereference component and the base element, wherein the second contactextends from an edge to a center of a surface of the base element. 4.The reference structure as defined in claim 1 wherein the semi-permeablereference component comprises a spray paintable material.
 5. Thereference structure as defined in claim 1 wherein the semi-permeablereference component comprises a screen printable material.
 6. Thereference structure as defined in claim 1 wherein the base elementcomprises a semi-permeable material having an anisotropic electricalconduction and an anisotropic thermal conduction.
 7. The referencestructure as defined in claim 3, wherein the semi-permeable referencecomponent is in electrical communication with the at least one of thefirst contact via the first circuit and the current collector via thesecond contact and the second circuit.
 8. The reference structure asdefined in claim 1 further comprising a meter in communication with thefirst circuit and the second circuit, wherein the meter is operativelyconfigured to obtain a first voltage from the first circuit and a secondvoltage from the second circuit, wherein the first voltage and thesecond voltage are indicative of the status of the cell, and the statusincludes a state of charge of the cell.
 9. The reference structure asdefined in claim 1 wherein the base element is disposed on an oppositeside of the electrode of the cell as the current collector of thebattery.
 10. The reference structure as defined in claim 1 furthercomprising a coating disposed on the base element, wherein the coatingis an electrical insulator comprising a plurality of particles and apolymeric binder, and the polymeric binder includes polyvinylidenedifluoride, polyvinyl alcohol, polyacrylic acid or any combinationthereof.